Tuesday, September 13, 2011

The Best Diet to Feed Hyperthyroid Cats

Hyperthyroidism is the most common endocrine disorder of cats, and is one of the most common medical problems seen in small animal practice. Surprisingly, despite the fact that nutritional factors and cat food likely has a role in the etiopathogenesis of this disease (1), there are only limited published recommendations about what to feed these cats.

The question, “What’s the best diet to feed my hyperthyroid cat?” is an extremely common one that I get from concerned cat owners. I’m certain that many of you get the same question.

With the recent introduction of the Hill’s y/d diet (2), the iodine deficient diet which, according to the company website “restores thyroid health,” I thought that my opinion of what diets should be fed to cats with hyperthyroidism might be of interest.

In this post, I’m not going to talk specifically about y/d or any other diet, but which types of food and nutrients hyperthyroid cats need in general. I’ll specifically address the pros and cons of y/d in my upcoming blog posts.

The Many Metabolic Problems Facing the Hyperthyroid Cat

When secreted in excess, thyroid hormones have profound metabolic effects on the whole body, and dysfunction of multiple organ systems (CNS, cardiac, gastrointestinal, hepatic, and renal) is common in hyperthyroid cats (3-5).

Weight Loss and Muscle Wasting
Weight loss, despite a normal to increased appetite, is the classic and most common signs seen in cats with hyperthyroidism (3-5). These cats lose weight because their hyperthyroidism accelerates their metabolic rate and body’s energy expenditure; they are burning up their food calories faster than they can consume their daily meals.

It’s important to realize that hyperthyroidism is a catabolic state. The progressive weight loss and muscle wasting that is so characteristic of feline disease is caused by increased protein catabolism leading to a negative nitrogen balance (6,7).

When hyperthyroid cats first lose weight, the case can usually be first noticed as a loss of muscle mass in the cat’s lumbar paravertebral area. Despite this loss of muscle mass, most mildly hyperthyroid cats retain their “belly” during the initial stages of their thyroid disease and may even have a higher than ideal body condition score.

With time, severe muscle wasting, emaciation, cachexia, and death from starvation can occur if the cat’s hyperthyroidism is left untreated (3-5). In hyperthyroidism, the cat’s body consumes its own muscle tissue to get the protein it needs to sustain its carnivorous life.

Even with treatment of hyperthyroidism, recovery of muscle mass and function may be prolonged, lasting several weeks to months. This is especially true if these cats are not provided with enough protein in their diet to rebuild and maintain their lost muscle mass.

However, the actual metabolic changes are actually much more complicated: hyperthyroidism frequently causes moderate to severe “endogenous” insulin resistance, as demonstrated by high resting serum insulin concentrations and an exaggerated insulin response during an IV glucose tolerance test (8,9). This insulin resistance is associated with a decreased glucose clearance (impaired glucose tolerance), which is indicative of a prediabetic state (See Figures below).

Serum insulin concentrations in response to intravenous glucose tolerance test in 11 healthy cats, 15 cats with untreated hyperthyroidism, and 6 hyperthyroid cats after treatment (9). Notice the exaggerated insulin secretion in the untreated hyperthyroidism cats, which becomes even worse after treatment. Such high insulin concentrations is diagnostic for "endogenous" insulin resistance.

Occasionally, an untreated hyperthyroid cat will develop overt diabetes mellitus. Many of these diabetic cats will develop moderate resistance to the injected insulin, with poor diabetic control.

Surprisingly, the insulin resistance and prediabetic state so common in hyperthyroid cats does not always improve and may even worsen despite successful treatment of hyperthyroidism (9): see Figure above. This indicates that hyperthyroid cats may have long-lasting alterations of glucose tolerance and insulin secretion that cannot always be reversed by treatment. In accord with that, some of these hyperthyroid cats (not diabetic at time of diagnosis) will go on to develop overt diabetes mellitus in the months to years after treatment of hyperthyroidism.

Sarcopenia of Aging
In addition to loss of muscle mass from the catabolic effects of thyroid hormone excess, cats also tend to loss muscle mass they age, independent of their thyroid status. This phenomenon, referred to as sarcopenia of aging, is also common in elderly human beings (10-12). The term age-related sarcopenia is derived from Greek (meaning "poverty of flesh") and is characterized by a degenerative loss of skeletal muscle mass and strength, as well as increased muscle fatigability.

In adult cats, maintenance energy requirements decrease by about 3% per year up until the age of 11 years, and then actually start to increase again (13). This contributes to a tendency of senior cats to lose muscle mass if their energy needs are not met. Lean body mass of aging cats drops dramatically after 12 years of age, and by age 15, cats may have a mean lean tissue mass that is a third less than cats aged 7 years or less (13, 14). Body fat also tends to progressively decrease in cats after the age of 12 years; this combination of reduced lean mass and body fat contributes to weight loss experienced by many elderly cats.

The ability to digest protein is also compromised in many geriatric cats. After the age of 14 years, one-fifth of geriatric cats have reduced ability to digest protein (13-15). Reduced protein digestibility in geriatric cats seems to occur in parallel with reduction of lean tissue and it might predispose them to negative nitrogen balance. (16).

Although moderation of calorie intake might be suitable for some mature cats, it does not appear to match the needs of most geriatric cats. In contrast, it seems more logical to use highly digestible, energy-dense food for geriatric cats in order to prevent or slow their decline in body weight and lean body tissue (13,16,17).

Reducing protein intake in geriatric cats, at a time when lean tissue has been lost, is contraindicated. Geriatric cats seem to have nutritional requirements closer to kittens than to mature adult cat.

Diet Recommendations for Hyperthyroid Cats

High Dietary Protein
As discussed in my last post about what to feed normal cats, obligate carnivores, such as the cat, are unique in their need for large amounts of dietary protein (specifically, dispensable nitrogen) that separates them from omnivores and herbivore species (18-20). This absolute requirement for dietary protein intake in cats is critically important when formulating a diet for hyperthyroid cats, in which protein catabolism and muscle wasting is universally present.

Protein is the primary macronutrient responsible for maintenance of muscle mass. Restoring and preserving any remaining muscle tissue in cats treated for hyperthyroidism depends upon the cat consuming a diet with sufficient amounts of high-quality protein.

This recommendation for higher amounts of dietary protein does not change once euthyroidism has been restored. The dogma that all older cats should be fed reduced energy “senior” diets must be questioned based on what is now known about the increasing energy requirements and nutritional needs of older cats (12,13).

In most geriatric cats, logic dictates the use highly digestible, energy-dense food mitigate the decline in body weight and lean body tissue and to avoid protein:calorie malnutrition (12,16,17). Protein reduction for this geriatric life stage, at a time when lean tissue is being lost, is contraindicated. Geriatric cats seem to have nutritional requirements closer to kittens than to mature adult cats.

Low Dietary Carbohydrates
Since most of these cats also have subclinical diabetes —as evidenced by their mild hyperglycemia, glucose intolerance, and insulin resistance— feeding a low carbohydrate diet (<10% of total calories) also is strongly recommended (21).

Feeding a low carbohydrate diet will improve insulin sensitivity, reduce the need for exogenous insulin, and help stabilize glucose metabolism in these cats (21-23). This may prevent the development of overt diabetes and control long-term obesity in these cats after successful control of the hyperthyroidism.

Feeding Your Hyperthyroid Cat: The Bottom Line

Like normal and diabetic cats, I believe that it makes sense to feed most hyperthyroid cats a diet composition close to what they would be getting in the wild. That would be a diet composed of approximately 50-60% protein, 5-10% carbohydrates, and 30-50% fat.

Because older cats also loss lean muscle mass in association with the “sarcopenia of aging,” this diet composition needs to be continued even after one treats the cat’s hyperthyroidism and restores euthyroidism.

Check out this website (http://binkyspage.tripod.com/foodfaq.html), which gives you a breakdown of the composition of the various prescription and over-the-counter diets. It turns out that many of the over-the-counter diets have a better composition of protein and carbohydrates than you might have thought — even better than many of the more expensive prescription diets. Very few of my hyperthyroid cat patients require a prescription diet to fulfill their nutritional needs.

As I discussed in my last post, the composition of almost all dry food cat diets are much too high in carbohydrates and most are too low in protein content. That is why I believe it's best to limit the amount of dry food that is fed to cats, or even better, not feed dry food at all.

Cats with advanced renal disease (IRIS Stage 3 or 4) may need lower amounts of dietary protein to lessen uremic episodes (24). However, at least in early to mid-stage renal disease, lowering of the serum phosphate concentration is much more important in management than dietary protein restriction, and this can be easily accomplished with phosphate binders without lowering the protein content of the diet (25,26). It may seem impossible, but no studies have conclusively demonstrated that severe restriction protein alone will prevent further deterioration of kidney function in cats (27).

The major problem that I have with some of the prescription kidney diets is that they restrict protein to the point that some cats – especially those with concurrent hyperthyroidism - will continue to catabolize their own muscle mass despite adequate control of the thyroid condition.

Once we have selected a few diets with the required composition breakdown of carbohydrates, protein, and fat, we next have to look at the ingredient list. Not all of the proteins in cat foods are equal in quality. Remember that quality meat is the best ingredient in a food and that meat by-products are a close second. Some vegetable and grains are fine, but they may supply a less bioavailable form of protein for cats and should not be the primary source of dietary protein.

Remember that when deprived of protein, carnivores will continue to break down muscle tissue to create the energy they need (18-20). By feeding only high-quality protein diets, we will help restore the cat’s muscle mass and improve strength and agility.

Let's use some common sense and not perpetuate the muscle wasting in these older cats by feeding diets that are too low in poor-quality protein.

151 comments:

Having lost 3 senior cats to hyperthyroidism in one year, I now have one, Doodles, a 16 year old female, that was slipping away from the symptoms I knew all to well. I researched quality high protein foods and came up with a mix of EVO Turkey and Chicken (50% protein) and Blue Wilderness (40% protein) Supplemented by at least one serving of canned chicken a day. The trick is many small servings during the day, all the way to bedtime, and plenty of fresh water in several rooms she frequents during the day and night. I've been able to stabilize her weight, her coat is beautiful and there is no vomiting or diarrhea, but a looser stool than my healthy younger cat. I choose not to medicate her because the medication upset my other 3 cats systems so dramatically. It has been a year since I started the high protein, high quality diet, fed in small portions at will. At this point, the quality of life for Doodles remains good.

Thank you for this article. I get so disgusted at vets who preach low protein Rx diets for kidney issues (full of by-products and fillers and chemicals) at the expense of the rest of the body.

Our "Belle" (18 or 19 years old) was diagnosed with both CKD and hyperthyroidism almost 3 years ago. It's tough trying to juggle both, as it's her thyroid that's keeping her kidneys going. She's on a relatively low dose of Tapezol but I have to very gradually increase it now and then, to keep her from being too hyper, but not so much that it sends her kidneys over the edge.

Recent blood work showed her CKD hasn't worsened. I feed her high-quality, no-grain raw (with some veggies) and canned, with a little organic squash baby food topping now and then, plus salmon oil and extra vitamin B, C and E and some other supplements for her heart. I always add extra water to her food to make sure she's getting enough water (SQ fluids are difficult with her so, she gets them very infrequently), and she eats probably 5-7 times a day.Unfortunately now there is more muscle wasting in her legs so I will feed her even more often.

Hi Dr. Mark! Thanks for your time & information. I'm looking for anew wet food for my hyper-t kitty and am hard pressed to find one with the 50% or more protein you mentioned. Just to be sure I know what you mean, am I looking for the crude protein percentage listed on the can, or the overall content. For example, EVO lists the crude protein at 9.0%, but the product description says 95% chicken & turkey. Thanks for your help!

My vet persuaded me to stop my cats medication (which we had a lot of problems getting the correct dosage with) and change to Hill's Y/D. All well and good but my cat has lost a lot of weight in the last 4 months. He had 4 teeth out today which we hope is the cause of the weight loss. My problem is this: bad teeth or not, I still don't believe that the Y/D is giving my cat enough nutrition and want to feed him additional cooked chicken/turkey or liver as well as the Y/D to get some weight back on him. My vet is dead set against this idea and says I must stick to the Y/D as its iodine free. But I've researched on the internet and poultry is apparently iodine free so what shall I do? This issue is particularly pertinent now as post op, the Y/D soft food is much too rich for my cat and he keeps throwing it up. I really need to get some decent food into him and fast! What shall I do?

Unfortunately, as long as you are using the Hill's y/d to control your cat's high T4 value, you cannot give any other food. The only way to give low-iodine chicken or turkey woud be to feed those birds an iodine deficient diet so that their body would be low in iodine. And that's not going to be possible unless you raised the birds yourself!

It is very possible, and even likely, that part of your cat's weight loss is due to protein deficiency. Hyperthyroid cats need protein and y/d doesn't contain high amounts of protein, even for a "normal" cat. I'd consider another treatment for the hyperthyroidism so you can get your cat on a proper diet.

I've just been told my 18-yr old NM DSH tabby (Bud) has hyperthyroidism. Vet gave me Tapazole 5mg and said Hills y/d. I said no to the y/d. Bud has been in diabetic remission for 5 years and I do not want to give him food that may bring the diabetes back. He's been on a strict, canned food diet, which began with Fancy Feast, it was great for a couple yrs until he started vomiting every night, so we switched to two flavors of Friskies Pate, and he has been fine all this time. over the past couple weeks he has been losing weight and muscle mass, won't eat, and vomits during the night. It's like no vomit I've ever seen (always dark green, thick, and smells like his poop, even worse). The vet initially told me he had kidney disease and gave him an appetite stimulant, and did blood work. She called me three days later and said it wasn't kidney disease, but hyperthyroidism. His T4 was 5.1. I'm older and live alone, and pilling is nearly impossible. Though Bud is weak, he clamps his mouth shut like a bear trap, I can't even get my finger in his mouth to gently pry it open. I've tried hiding the pills in his food, pill pockets, a pilling gun, crushing and sprinkling in his food...it's like he can smell it and will not eat any of it. He refuses to eat his canned food now and I have been baking chicken for him - which he does eat, but very little at a time - he eats MAYBE 2 oz of food per day. He just vomited again but this time it was actual vomit, not the horrid green stuff. At this rate I know he's not going to last much longer. I want to be proactive with this like I was with his diabetes and get him healthy again. Prior to this, he weighed 15 lbs. Now he is at 10.5.I've looked at Dr. Lisa's food list and am now more confused. I don't know which would be best for him. Can you point me in the right direction, or tell me which food to buy? Sorry, I'm pretty distressed at this point. Any advice you can give is so much appreciated.Thank you so much!

Sorry to hear that Bud isn't doing well. I agree with your decision not to start y/d as the initial treatment for hyperthyroidism. Feeding a higher carb diet certainly could result in a relapse of his diabetes. Plus, this will not help restore his lost muscle mass, since y/d is too low in protein.

My main concern with Bud is the fact that he isn't eating well and is vomiting. Although his hyperthyroidism is not very severe, hyperthyroid cats should have a good appetite. Vomiting, when it does occur, generally occurs shortly after eating because they eat too much too fast. In an 18-year old cat, we always have to worry about other problems, concurrent to the hyperthyroidism.

Any older cat that isn't eating very well is likely to develop muscle wasting, not matter what the diet. Even if you are feeding a high protein diet, they still have to ingest enough of it to get the protein they need. In addition, other diseases can lead to enhanced muscle breakdown (cachexia of illness).

Was he eating better and not vomiting before the methimazole? From you email, it sound like he was not. If you haven't done so, an abdominal ultrasound would be my next step in diagnosis to help exclude other problems.

If nothing else is found and you decide to continue the methimazole, you might want to talk to your veterinarian about using transdermal methimazole instead of the pills. Cats tolerate that form better - just apply some gel to their ear pinnae twice a day.

Hi Dr. Mark! I am a veterinary from Portugal and I am struggling with a case I've been following for a year. I have a 15 year old DSH cat with HT, controled with metibasol, but he has diarrhea that doesn't respond to any medication or food... I tried hipoalergenic food (royal canin, hill's (z/d,y/d)), intestinal food, tried antibiotics (metronidazol, neomicine), did fenbendazol,probiotics, pancreatic enzimes and even a little steroids! Every test is ok, except for the echography that shows a "reactive intestine". I'm running out of ideas... Can you help me? Thank you! Filipa Cordeiro

Most hyperthyroid cats with severe diarrhea have primary G.I. disease rather than thyroid-related diarrhea. This is especially true in this cat, where you have controlled the hyperthyroidism with San antithyroid drug.

I don't have any answers - you probably need a small intestinal biopsy to rule out lymphoma vs severe inflammatory bowl disease. If you haven't done so, you should also measure the serum cobalamin, folate, and PLI levels to to help in your workup.

You know, in response to some posts below, I recently had the same issue with our vet pushing the Science Diet Y/D on us DESPITE all of my cat's thyroid and kidney levels normalizing in ONE MONTH'S time on a purely raw food / veggie / homemade chicken soup diet. This is in addition to her medication... half a Methimazole in the morning and half at night and 100CCs of fluids every night. Her holistic vet also put her on one Azodyl a day which is amazing. It literally sucks out the toxins from her bloods without her kidneys having to process them. Also homeopathic drops for her immune system and a supplement for enteric support. We are, after all, supposed to treat not just the disease, but our cat's entire body, as these illnesses can affect more than one organ.

Back to the Science Diet issue... please don't be swayed if your gut tells you it's not right for your cat. I found a Wallstreet journal article that explains why so many vets recommend Science Diet, and it involves incentives and Hills paying for a lot of vets' education, and after some additional research, I found out that most vets are not educated in pet nutrition! So they are going to recommend the one thing they know and have been brainwashed to recommend, Science Diet. I have stopped taking her there, as I believe it is very unprofessional to recommend ONE thing without researching other options. On my own, I found that the Veterinary School at UC Davis has a Nutrition Department that can formulate a special diet for your pet based on his / her health condition(s). I found this extremely helpful.

The fact is, it IS a delicate balance to have a cat with hyperthyroidism AND kidney disease, and most vets will recommend a low protein diet for kidney disease, but this has not proven to improve kidney values. The study was based off of a study done on rats, which have VERY different needs than cats (AND humans for that matter...but that's a different topic).

Hi Dr PetersonI wrote on your blog earlier today about my 16 y/o female cat who was diagnosed last fall with hyperthyroidism. I've been doing more reading and see that it's not only phosphorous levels in supplementing the Hills y/d diet I need to be concerned about but also iodine levels that will counteract the Hills diet. What do they say about a little knowledge? I'm not sure how long it will take now for her thyroid levels to go up as she's still only eating the Hills diet b/c Ive been adding a little tuna in oil to it. I'm not sure what the outcome will be but I guess the bottom line is that I couldn't watch her starve herself to death. The most recent check in with the Vet (before I started supplementing the Hills diet with tuna) was that her thyroid level and electrolytes were good but that her kidney (urea) level was quite high in the 20s I think. Her weight was down to a little over 5 lbs. I am grateful that she has lived this long (you see she's a Siamese with lots of personality and attitude and she thinks she's human) and I'm just hoping that when she dies that she has a good death and maybe that will mean euthanasia, I'm not sure. I'd appreciate it If you have any recommendations or suggestions. Thanks so much!

You are right-- if a cat isn't eating a prescription diet, such as y/d, what good does it do if the cat is going to starve to death! I assume that you have already tried methimazole or carbimazole and those drugs failed.

You could add L-carnitine (open a 250-mg capsule and mix into her food). That drug is available at any health food store. It may block some of the actions of excessive thyroid hormone and make your cat feel a bit better once the levels start to go up again.

Hii Dr. PetersonI just wanted to check in and say thank you so much for your recommendation to try L-Carnitine, 250 mg. back two months ago. My cat is doing so much better, it's quite hard to believe. She started eating a can daily of Y/D. To entice her to eat this (and believe me she needed enticement) I've added the juice plus water from Clover Leaf, white tuna, vegetable broth and oil and mix the L-carnitine powder in and so she doesn't actually get any of the tuna itself. She continues to take Azodyl daily (I break open the capsule and mix it in a little cream early in the AM. She's better than any alarm clock at 6am.To respond to your question re: Methamazole; yes, she has had the topical ear ointment that controlled the thyroid values however I had to change to Y/D as I rely on others to come in and look after her from time to time and she was not very compliant with them. She has a bit of vomit about once weekly and other than that she definitely has her 'mojo' back:). I'm not sure what her values are at this point in time and right now there doesn't appear to be any reason to take her back to the Vet however I will take her in for a check up in the near future......Again, thank you so much!!

Hi, I just came across your site and find this conversation very useful. I have a 16.5 year old cat who was just diagnosed with hyperthyroidism. The vet didn't say anything about changing her diet, but did prescribe Methimazole liver and tuna flavored chews, 2x a day, which Marbles gobbled up happily. Until today. (She threw up twice last night, and I think she's connected her nausea to the chews.) My question: it appears from these threads that with a high protein diet, we can restore her thyroid condition to normal. Is this true?

Hi, I just came across your site and find this conversation very useful. I have a 16.5 year old cat who was just diagnosed with hyperthyroidism. The vet didn't say anything about changing her diet, but did prescribe Methimazole liver and tuna flavored chews, 2x a day, which Marbles gobbled up happily. Until today. (She threw up twice last night, and I think she's connected her nausea to the chews.) My question: it appears from these threads that with a high protein diet, we can restore her thyroid condition to normal. Is this true?

In addition to the higher protein, lower carbohydrate diet that I discuss above, I like to feed a varied diet. No all companies use BPA in the canned lining but it's difficult to find. In general, the small can sizes seem to be the best bet for canned foods.

I agree that fish foods should be limited but I don't believe it's necessary to totally eliminate them.

If you must feed a dry diet, you could try Purina DM, a diet higher in protein and relatively low in carbohydrates. It's marketed as a food for diabetic cats but I feed a small amount to my cats as a treat and they love it!

Interesting to read all the different ways to treat hyperthyroidism. My 18 year old cat has it. My vet has put her on the Y/D diet. It did help. She still has an appetite and the yd has kept her from vomiting. She has lost so much weight. She loves turkey and chicken. Why do you say that you cannot feed anything along with the yd diet?

My cat has been on Hill's y/d for the past year and it has been successful. The past few days he has turned picky. He has eaten small amounts of the canned food but that is it. I can tell he is hungry cause he goes crazy when I eat.

HiA week ago I was told my cat has "Thyroid problems" And was given 30 10mg Vidalta tablets and to come back in 6 weeks and they'll test to see if my cat is "fixed". He's nearly 14 years old and has had arthritis for at least a year. He weighs about 5 or 6 kg, so he's a big cat. The vet was busy when I picked up my cat so I was left to google what all this meant. After googling I just found horror stories! I don't know if the meds I've been given will harm my cat, what to look for etc. Some people just did what the vet said no matter how their cats were reacting. And I only have 30 tablets, that is not 6 weeks worth, I've read that they go back to hyperthyroid within 24 hours. I give him metacam every day and have j/d Feline mobility biscuits mixed with whiskers biscuits available at all times.I'm pretty much confused about what I should feed him, taking into account the arthritis. I've been feeding him 85mg Dine cat food (fish) as this seems to hide the pills the best. I pretty much have no idea what kind of food, man made or natural to feed him for all of this or even what the condition means overall. I don't want to go to the vet as I'm wary of them just prescribing things, but armed with hopefully unbiased knowledge, I will be able to navigate them much easier. Plus he never gets my cats gender right (he's a dude). Can you possibly give me any hopefully clear information about the food and that to help? To be honest I'm not even sure how to look for the correct percentage of whatever food and even how much of said food I should give him. Thanks!

If you go to www.catinfo.org, you can learn a great deal about how cats should be fed.

On the homepage of the catinfo.org website, the is a link entitled "Protein/fats/carbs chart" which will give you a breakdown of the dietary composition of many of the OTC (over the counter) catfoods. You can use my information to select a good canned food that will provide higher levels of protein and lower amounts of fat.

I've looked at the chart on catinfo and it lists all the cat foods that they don't sell in my country. The only product in Binky's page that may possibly be sold here is Friskies. I've been feeding him Dine Desire (which isn't on any chart) and whiskers pouches which from binky's chart seem to be bad. I feed my cat J/D Feline Mobility biscuits too, which I told me was a horrible diet. What else am I supposed to feed my arthritic, hyperthyroid cat? The vets told me there isn't really another option other than the biscuits. I can't afford a grinder to make my own cat food and there aren't really places to source rabbits etc, so I'm really at a loss. I can't even find a solid answer on whether it's a good idea to feed him 1 scrambled egg a day. And I'm not supposed to feed him fish? So far I've googled all these things for weeks and still haven't found a concrete answer. I pretty much feel like I'm poisoning my cat every day because I can't figure out what is good and what is bad. I am not asking for specific instructions just maybe some more information about the things I've raised. The labels on my dine do not give me any real information on the percentages of the proteins, etc. Where are the canned mice and birds when you need them?

If your goal is to increase the protein and lower the carbs, that should not be that difficult. You may have to call the pet food companies to find out what % of the calories make up the protein and carb content. We want the protein to be greater than 35-40% of calories (metabolizable energy or ME) - that's the most important. This is all discussed in detain at www.catinfo.org.

Our 10 year old cat was recently diagnosed with hyperthyroidism. Do you have any information on some of the natural remedies such as NHV Resthyro or PetWellbeing Thyroid Support Gold? Could these coupled with a high protein diet help maintain healthy thyroid levels?

The underlying cause of hyperthyroidism in cats is an overactive thyroid tumor. All of the natural remedies act to control signs of the disease, but they are only a temporary measure. The only way to cure the disease is by removal or irradiation of the thyroid tumor,

My hyperthyroid cat is thriving on the y/d. Though I was reluctant to put her on a sub-standard (IMO) diet of by products and processed junk, she's been on it about one year now. She is doing so well, I can't think of a better option for her. She's BARH, playful, fur has grown back everywhere, no GI symptoms, and all else is well. Even her toenails are normal again. I would like to do I-131 but the specialist doesn't think kitty is a candidate.

That said, what the heck is it about y/d that works? How is their pork iodine deficient? Do you think they are farming their own pork for this product? Or maybe they have a deal with a farmer to feed an iodine defficient diet for a few weeks (months?) prior to slaughter? I am so confused about how they do this. I could feed an iodine deficient diet to some chickens then feed these to my cats, but I have to know that's really going to work and there's not some other trick hills is pulling. I do notice they include L-cysteine in this diet and not in other prescription diets. I wonder if that's not the part that's suppressing thyroid function. Could it be Hills magic ingredient with it's ability to enhance excretion of trace minerals?

My kitty is on the meds and responded well at first, but I can tell he is declining. Very thin. We live in alaska and have plenty of fresh wild salmon that I have been giving to him every day in addition to his regular science diet kibble and iams wet food. Is the salmon ok for him? Do I need to up the dose of the meds? His labwork showed high t4 but nothing else that was out of range. He has been on the meds since july and he is getting twice a day, on oral med. due to our remote location, surgery and irradiation are not an option. Just trying to understand this disease. Thanks for your informative site. Can I continue with the fresh salmon?

Help! My Spotty is 15 1/2 years old. He is a total indoor cat. He was diagnosed with hyperthyroidism about 2 months ago. My vet suggested putting him on the Y/D. Since being on the food I noticed his lethargic, not cleaning himself and makes jumpy twitches. Just had him in to re-run his tests and she called yesterday to say his kidneys are terrible. They were fine 2 months ago! She said she spoke to specialist who told her we should keep him on the y/d. Now she wants to put him on meds for his kidneys. Today, I noticed he is having trouble with constipation. I don't want to pump him full of medication if some other type of diet will help him. He started on the prescription diet food a long time ago because he developed crystals in his bladder from the cheap cat food. I was hoping to have him around for a few more years.

Hello, thank you so much for all of this fantastic information! My 15 year old cat has been hyperthyroidism for maybe a year now. Long story short, I learned in January that my husband was not giving the cat his meds like I thought he was so I took over all the feeding and medicating of the pets. I took him off dry taste of the wild kibble and he is on rotating canned tiki, weruva & similar high protein low carb foods. He was supposed to get 1 5mg tapazole a day, but when I took it over, I started at a half, because I hate him being on meds. I also started feeding him a mid day feeding as well. Trying to go for about 80 calories 3 times a day, but he doesn't always eat it all. I feel like recently his face has gotten more sunken in, but I do not notice any other new typical hyperthyroid symptoms. I got him very slowly gaining weight, and is not acting cranky or anything else like he was off his meds. He did have diarrhea when I first started meds again, used fortiflora to encourage him to eat new wet food and it maybe helped with the diarrhea as well. He has lost half of his body weight in the past 2 years. He was down to 9.3 on 1/13 and is up to 10:6 lbs. So the only thing I am concerned with is his sunken in face but I am wondering if I should increase his Tapazole or leave it the way it is for now. I am considering a sure flap cat door to make a feeding box for him, so he can eat more often. http://www.pinterest.com/pin/222013456604841099/ or even a meowspace http://www.pinterest.com/pin/222013456604841064/

In reading the "newwoman" 2011 post, I luckily hit upon the same solution methodology -- small servings of protein given frequently during the day (poached fish & Whiskas packet cat food alternating) - but I warm the servings with a bit of water and microwave it 15 seconds. My 18 year old male cat is now thriving, and the coat is improving after one month of this treatment.

My 13 y/o part-Himalayan/Siamese, Zada, who I rescued when she was only 7 mos. old, was diagnosed with hyperthyroidism just yesterday. She was put on methimazole & loves her Fancy Feast. I've been slowly researching sites to see how I can help her have a great life as 2 of my "fur" babies who had this aliment had in the past. They were diagnosed at a much older age, though. My precious, Zoe (I have no idea why my keyboard will not allow me to place the accent mark over the "e" in her name?? As well as using what I learned in college??), passed away c/in 3 mos. p being Dx with thyroid CANCER at 17.5 yrs!! Dr. Mark, there was one product which read, "this product has been tested by the FDA & approved." Well, I'm a pharmacist. If it had been tested by & approved by the FDA, why is it so easy to obtain?? The meds. I get from my Veterinarian have the Federal warning label on them & if I can get it from the pharmacy, I have to have a written rx from my Vet. Just curious as to whether such herbal products, such as the one I just read, are effective?? I would love an answer, please as I'm not ready to watch her deteriorate quickly!! Thank you very much!!! PS: Still interested in how people are feeding their babies, etc. PPS: She looks more like a Himalayan, but is finicky as her previous predecessors.

Herbal products may help the cat's symptoms but do not lower the high thyroid levels or do anything about the thyroid tumor that is causing the problem. Take a look at my other posts, which should help you decide on the best treatment for your cat.

My 17 yr cat is scheduled for the i131 treatment in 4 weeks but is losing weight despite feeding a raw diet. He cannot tolerate the medication and am wondering if the yd would be a good interim food until the treatment can be performed. I also would like your opinion on Feline's Pride version of iodine free mix that you add your own meat to.

First of all, why do you have do wait for another month to treat with radioiodine? (We do the treatment at least once every week!)

I would not start y/d because that diet takes at least a month to work and may interfere with the radioiodine treatment. The iodine free mix doesn't help because all meat contains iodine, unless the cattle or chickens are fed no iodine (which is never the case since iodine is an essential nutrient).

I have a 17 year old cat who was diagnosed with hyperthyroidism 5 weeks ago. She was prescribed Felimazole 2 x 2.5mg per day. Into the 5th week she developed a rare side effect of the drug and the vet recommended that I stopped this & try the y/d diet instead. She has only been on this diet for 3 days but is only eating 1 can of 156g in 3 days whereas the recommended intake should be 1/2 to 3/4 tin per day. The vet also gave Vidalta in case she refused the diet food. My concern is that she is losing weight & is showing new symptoms of hyperthyroidism. Having read your comments and blog, I would be interested in your view as to wether I should persevere with the diet or start her on the new medication. She is also on Mitrazapine to stimulate her appetite.

I'm happy I found this site!Our 14 yr old cat was allergic to the thyroid medicine and almost died from it so we opted to change her diet to almost pure meat. Initially it was raw hamburger (ground in store) which brought her back to life but now I'm home canning poultry (including gizzards and bones in a vegetable trimmings/egg shell stock). Catinfo.org has a lot of information but recommends against only home canned food because of some perceived loss of nutrients. However I mash the bone tips up with the meat when I feed the cat and add a bit of vinegar to leach the calcium out of the bones prior to canning. Shouldn't this be okay? You had mentioned l-carnitine as a supplement. Could I just add bits of beef to the jars or slip a pill/powder/gelcap in at feeding time for that? BTW for other people, home canning with tattler reusable lids is pretty cost effective.

If you are going to home cook and feed an all-meat diet, I would consult with a nutritionist to ensure that this is balanced (catinfo.org is a good place to start with a phone consult).

L-carnitine, as a good diet, can help with hyperthyroidism, but will never control the high T4 level or cure the tumor that's causing the problem. Talk to your vet about the best treatment in your cat.

Our 17 year old cat was diagnosed last year with hyperthyroidism and put on the y/d diet of both wet and dry food. He has always been fed on dry food (Science Plan) supplemented with cooked meat and fish. He does not tolerate mushy cat food well, it causes him to vomit. He didn't take to the wet y/d but eats the dry stuff, albeit in smallish quantities. He has lost lots of weight, which I can now understand from reading your advice, is muscle loss. His coat has also become very matted (he is a british blue). My main concern is that he should not be in pain, and after reading this blog, I'm wondering if I should change to the tablets and a high protein diet. Is there any evidence about switching from one form of treatment to another?

Talk to your vet, but I would certainly consider switching to a better diet and starting antithyroid drug therapy. It should certainly work better than the current management, which looks like it has failed.

I'm happy to have stumbled on this thread in a desperate Google search to find any suggestions for my 19 y/o kitty. She was diagnosed as hyperthyroid approx 4 years ago. Since then, it's been an ongoing roller coaster of increasing and decreasing tapazole/methimazole. She has always been a very small cat, never really more than 5-6lbs. Three weeks ago, we observed some very concerning behaviors starting with urination all over the house, escalating to stumbling ("drunk" walking) and falling over which led us to an immediate vet visit. The exam results indicated that while her thyroid seems to be currently regulated quite well, her kidneys are ultimately failing slowly. However, because she was still eating/drinking and displaying her normal loving behaviors, our vet did not recommend euthanasia yet. It's been 3 weeks and while she's still an old lady (and still urinating around the house), she has made a surprising come back...walking fine, even a little pep in her step. We are currently administering 100cc fluids twice a day and 2.5mg methimazole once a day.

The reason for my search is that we want to do everything to maintain a quality of life for her while she still seems happy to stick around. However, we are still struggling with her weight loss and inability to feel satisfied. She is now 3.7lbs (skin and bones) and on a strictly wet food diet (fancy feast classic - which, according to the chart is equal to/greater than 50%). She begs regularly and we accommodate with small amounts of wet food throughout the day. At this point, she's begging and whining for food constantly, and even though she eats some to most of what we put out for her, she never seems to be satisfied.

I've read through this post and skimmed some of the comments...I'm just wondering if you have any advice on what we might be able to do under these circumstances. We've toyed with the idea of making her meals instead of continuing to try different wet foods but I'm frightened it'll do more harm than good. Any advice or suggestions you might have is very much appreciated!

It doesn't make sense that she would be so hungary and emaciated if her hyperthyroidism was well regulated. If that is true, then something else, other than kidney disease, is going on. I'd talk to your vet about a further workup, especially for gastrointestinal disease.

Fancy Feast isn't the best diet if the kidneys are failing (too high in phosphate). I'd check out catinfo.org and think about a dietary consult with Dr. Lisa Pierson (at catinfo.org).

I read articles and journals on the internet nearly every night and I am just more confused. Especially with a very, very, very picky cat. She has normal-high hyperthyroid, is in the beginning to middle stages of renal failure, has constipation dominant IBD/maybe megacolon (takes cisapride, miralax and enzymes) although has also been having some loose stool as of late which is strange and allergies. I just don't know what to feed her but she has been losing weight very quickly and her fur has started to lose it's shine. I found that taking her off of those branded "human grade" pet foods like BFF has helped some symptoms particularly thirst (they are quite high in sodium which I did not notice at first) and hypercalcemia. She is extremely hard to please and would rather not eat than eat something she does not approve of. Putting a bit of salmon broth over it just does not work. Her vet is mostly concerned about thyroid and calcium more than anything else. I give her subcutaneous fluids every so often when I notice she is drinking a lot. I add water to all of her foods as well as squash. Vet suggested perhaps folate but doesn't really believe in supplements. We cannot afford a whole lot anyway. I have thrown out so much pricey food that she refuses.

I wonder if you could help me. I have a 15 year old cat who has been mostly feral all his life. He began losing weight last fall, I assume he was probably around 10 - 12 lbs. to start with. I was able to get ahold of him a week and a half ago and he was found to have hyperthyroidism, and exceptionally bad teeth and gums. At that point he was 5.2 lbs., and he stopped eating altogether, dropped to 4.8 over that weekend. He is now on Felimazole 2.5 mg twice daily, and Clavamox 1 ml twice daily. He is too fragile for surgery at this point and his gums are too infected anyway. I started just over a week ago giving him Hill's A/D with a syringe, and Nutrical in a syringe several times daily. He was having diarrhea and throwing up. He had been eating some canned tuna fish but he won't eat that anymore, and he won't eat any regular canned cat food, but oddly he eats a tiny bit of dry food. I found out a few days ago that he seems to love baby food, so I have backed off on the A/D and the Nutrical, and have only given him a small amount of those with a syringe since he hates that so much, and he eats SOME (but not much) of both, on a plate. He still has diarrhea and some throwing up, but both seem a bit better. My questions are, is the baby food OK for him (all meat, nothing else) and how much total food and total calories should I be giving him? Currently he is eating about 2 jars of the baby food a day, and more than that today, at 60 - 100 calories per jar, depending on the type. Should I still be giving the A/D and Nutrical with a syringe? Also at his tiny emaciated state, do you think he has a decent chance of recovery, and if so how long before he might be able to have his teeth removed? I forgot to mention that surprisingly, all his other values were either normal or only very slightly above normal, so there are no kidney problems or anything. Also, do you think stress may be keeping him from eating, in addition to the teeth? One reason I was able to so easily catch him is that his 17 year old mama kitty just died on June 1st, and he seemed to really miss her, and even started following me around. Now, I'm keeping him indoors due to his condition and having to give him all these meds, and he seems to be pretty unhappy about that as well.

You and your vet need to determine what the underlying condition/problem is that is preventing your cat from eating. If it's the teeth, then that problem must be taken care of, but most cats with terrible dental issues will still eat. Baby food may be good for human babies, but it is not an appropriate food to feed to cats for longer than a day or two. Talk to your vet. If you don't do something soon, you cat's prognosis indeed sounds grave.

Hi, I have a 17 year old cat who was diagnosed with hyperthyroid a couple of years ago. She was prescribed the Hills Y/D diet and while it did bring her lab results (T4?) back to normal, it did absolutely nothing for her weight - which continues to drop - or her body condition. All of her other labs were normal with no other physical conditions found besides arthritis.I go to a vet hospital that has several vets practicing and they seem to be unsure about the Y/D diet and what she can/can't have. I now understand the purpose of theY/D diet is to be iodine deficient. It states the iodine content is .2mg/kg.Anna is down to 5.5 lbs now with very low energy, thinning hair, and not very happy. She doesn't like the Y/D food, she eats out of necessity rather than wanting to. She has no problems eating dry food - she'll eat her brother's food (Merrick Purrfect Bistro Salmon) with no problem whatsoever. Neither cat will eat wet food of any brand.

So my question is, it should be safe to supplement her Y/D with chicken thighs (broiled, no skin) and other meats containing 0mg of iodine, right? One vet said no, one said it'd be okay. I'm confused and I don't want her to suffer, not eat, and eventually die from starvation as some hyperthyroid cats do.:(

If chickens are fed a diet with iodine in it, they will have iodine in their meat. These charts are rough estimates but cannot pertain to all meats. It's clearly been shown that adding chicken will interfere with y/d working.

Hi Dr. Peterson, thank you so much for making so much of this information available.

I'm in a similar situation to Jessica, as we have an 18+ yo cat that's been diagnosed as hyperthyroid for about two years. She's always been a small cat (6-7 lbs), but was down to about 5 pounds when the vet put her on y/d. We weren't really offered other treatments, and I can only assume that's because she's a senior kitty. After about 4 months on y/d, her thryoid levels returned to normal, and she went up to about 5.5 pounds.

She also has kidney disease, and is on Amlodipine (.25mL/day), which is keeping that in check.However, she has never been a fan of the y/d, and will sometimes just not eat. She is often trying to eat whatever our other kitty has in his bowl, or even what's in the dog's bowl. Over the two years, we have given her occasional treats of chicken (we make chicken and rice for our dog), and this has never affected her quarterly throid panel check. Within the past two months or so, she's decided not to eat her feed more often than not, but is obviously hungry and wants the other animals' food. I weighed her at home, and she was down to 4.7 pounds...she feels like just skin and bones.

I've been doing a lot of searching online to find foods low/free of iodine that I can supplement her food with more regularly (in addition to the occasional pieces of chicken she gets anyway) and I found the same chart that Jessica mentioned above. I ended up buying chicken thighs from a local farmer we use since many chickens in the store are injected with saline. She loves the whole chicken meat, and I feel comfortable that it's as iodine free as possible (we actually see the chickens roaming at the farm). I would also like to find a cat food though, that has similar qualities to the y/d, and I've come up with Rad Cat and Tiki Cat as possible options. I've also found the supplement called Thyroid Gold, but I'm not sure if that's worth purchasing either, so I'd love to hear your thoughts on that.

I read your statements above that anything given with the y/d will make the thyroid relapse, but I'm wondering why other manufacturer's can't also create a low iodine diet to offer since y/d doesn't have any medication like other Science Diet foods.

At this point, we're weighing her quality of life vs. selfishly extending her life. I don't want to make things worse for her, but I don't want her to starve to death either. We adopted her as adult kitty, so we know she's at least 18yo, but she could be older. She obviously wants to eat, but she doesn't want to eat the y/d, so we're struggling with what to do at this point.

Hi. My 9 year old cat has been on vet prescribed diets for 6 or 7 years to promote weightloss, which haven't really worked.. R/D, M/D, back to R/D, and for the passed year or so Metabolic. This week she was diagnosed with early stages of hyperthyroidism!! Which I wonder if was caused by the metabolic diet. Anyway, my faith in 'vet knows best' is now shaken so I have been trying to find alternatives to the Y/D diet or drugs that they recommended. She only has a reading of 49 which i thought might be able to be reversed by raw meat, thyroid support gold (if I can find that in NZ), and colloidal silver. Although I saw you said hyperT can't be reversed by protein alone. As yet we have not started any treatment, just raw chicken tonight which I now understand probably contains iodine. She has been a big girl her whole adult life (currently still 5.94kg) and while we have struggled to get her weight down I am now devastated by the thought of her wasting away.I already know what my vet recommends. What treatment would you recommend?

Hi, my apologies if I have numerous posts up here, they keep disappearing and I'm not sure where they're going..

I have a 9 yr old cat who has always been a big girl (currently still around 5.94kg). I have had her on various vet prescribed diets to promote weight loss for 6 or 7 years.. R/D, M/D, back to R/D and for the passed year or so Metabolic.

This week I was told she has early stages of hyperthyroidism, a reading of 49. The vet recommended Y/D diet or drugs, however I decided to try to find alternatives and thought a raw diet, thyroid support gold (if I can find it in NZ), and colloidal silver sounded promising. I have read you telling someone protein alone won't cure it though, and I now realise the chicken I fed her tonight probably contained iodine.

It's ironic that we have worked so hard to get her weight down and now I am devastated by the thought of her wasting away. I can't help but wonder if it was the diets that gave her this condition as she is so much younger than all the other cats on this post. We haven't started any treatment or switched diets yet. What treatment would you recommend? Is it reversible at this early stage?

My 18 year old Mooky could'nt take any medication and refused to eat the Hill's Y/D wet food (which BTW no cat should be on long term). I was watching my beautiful boy waste away in front of my eye's, he lost over a kilo in 3 weeks and the vet asked me to consider euthanasia.

It's taken a lot of time/research to keep him alive and I feel I should share my knowledge and success in case it may help others.

I started to cook Mooky a home made low iodine diet, after one week on this diet (which he loves if I get the mix right) he started to gain weight and was back to his normal self. After one month he was back to his normal weight and the vet confirmed his levels had dropped to a healthy level and to keep going with the diet.

Mooky has been on this diet for 5 months now with no issues, he is due for another set of tests this month so I will update you if anything changes but below is the diet that I feed my beautiful boy.

New Zealand Leg of Lamb, I spend £14.00 (cover, slow roast to cook medium rare... Do not add anything) (Don't stress if you cannot get NZ lamb any lamb will do but NZ grass has hardly any iodine so the meet will have lower levels than other lamb) 1 quarter of a packet of Quinoa (add 3 times amount water, microwave for 20-30 minutes) 1 quarter head of cauliflower (cook to tender) (cauliflower helps to stops the absorbation of iodine) 1/2 grated raw carrots ( added for bulk and vitamins )

Strip the lamb from the bone and blend it to a paste, don't forget to scoop out the bone marrow, you can also add water or if bothered make stock from the bone. blend the quinoa really well to a paste Blend carrots and cauliflower Then mix them all together and pack into plastic freezer bags and pop in the freezer.

You can always test the mixture with your kitty as you go along slowly adding more veg and quinoa. (Don't make the mixture too wet, try to keep to normal wet food consistency)

I cannot give you exact amounts as I'm just a normal person trying to keep my boy alive... there have been times where I added too much quinoa and he wasn't so keen so I guess you will just have to adjust it to what your little kitty likes.

Yes, it's a big old pain in the backside doing this but I only have to do this once every two weeks... for me its worth it... to have my boy back to normal makes me happy!

You also need to stay in control and do not be tempted to give your kitty any other treats (this is very hard)... Mooky will eat the Hills Y/D dry biscuits so I tend to give him these as a treat... I also keep back some of the lamb to hand feed as a treat.

I have a question about the amount of iodine in cat food. I have a 12 cat, diagnosed with Hyperthyroidism. Her level was 9. She has lost 1 lb. mostly in muscle and is now 8lbs.. She is otherwise healthy. I choose the Hills y/d diet, but am not happy with the low protein/high carb ingrediants. They show 0.2 mg/kg of iodine in the canned and dry version. I have researched Primal Pet Foods (Raw Food) and they show a level of iodine of 0.12 ppm in all the lines of their food (pheasant, rabbit, chicken, and beef. My question is if Hills is saying you can stabilize/ restore thyroid health in 3 weeks, can't a person feed Primal raw with it's lower iodine and get the same results?

It's difficult to make a diet that is deficient in iodine. If Primal Pet Foods (Raw Food) level of iodine of 0.12 ppm equals the amount of Hill's diet, then it should work but I believe that's much higher in iodine. Ask the company.

My 12 year old Siamese is severely traumatized by having to go to the vet. In fact, on this recent visit he had to be sedated in order to draw blood. Which I will never do again after a reaction to the sedation (compulsive twitching hours after.

I brought him to the vet after noticing some weight loss (which he needed) but mainly because for years he has had continual issues with regular vomiting. Like clockwork every few days he will vomit (clear bile) about 15-30 minutes before feeding. Previous vet visits showed nothing but possibility of hairballs but I decided to take him this time even with his extreme fear of leaving the house.

The blood work shows that he has hyperthyroidism and he was prescribed transdermal methimazole which I am reluctant to give him due to side effects and trail and error with correct dosage. The cat shows no signs of lethargy, pain/distress, etc other than the weight loss and vomiting which he has had in different forms (over eating, nerves,etc) since I adopted him as a kitten. I fear that the trauma of taking him to the vet for checkups is far more traumatizing to him than affects of the disease thus far (though I am a doctor my no means, just a very concerned pet mother).

In researching the disease and treatments I came across a holistic alternative called Thyroid Support Gold - Cat Hyperthyroidism Support sold by petwellbeing.com (http://www.petwellbeing.com/products/cat-hyperthyroid). Have you had any experience with this product as a possible treatment for hyperthyroidism? I asked my vet about it and he said that he could not offer an opinion.

The holistic medication may cover up the clinical signs, at least for awhile, but are not a good choice in my opinion. Hyperthyroidism is a progressive disease - caused by a thyroid tumor that will continue to grow unless surgically removed or irradiated. I understand that your cat was traumatized but it sounds like you (and your cats) might need another vet or a different hospital. Going to the vet should not be a bad experience. Alternatively, you can find a vet that will do house calls and have the rechecks done in that way. Good luck...

I have a 15 year old long haired tabby. She was diagnosed with hyperthyroidism in December last year. I was offered the option of an operation to remove the thyroid gland - which I'd done with another cat, tablets (hopeless to administer with her) or radiation treatment which I rejected on the grounds that she would be away from home for up to two weeks, which would be traumatic for her. It was suggested that I try the y/d diet and this is what she's eaten ever since. Only the dry food as she won't eat any kind of wet food, I tried the y/d tinned, she wouldn't touch it.

Recently (in the last month) her fur has started to mat horribly around her neck and on her hind quarters despite regular brushing and it feels coarse and dry, falling out in areas. On cutting out some of the mats I realised there are more bald areas that I realised. In the last few days her fur has become particularly bad and she's barely eating. She's begun to vomit more frequently, always a bit of a puker, but now sometimes there's very little in her stomach to vomit, and she yowls loudly. All of these I recognise as symptoms of her condition.

I'm horrified to come online and discover vets who disagree with the y/d diet on the grounds of insufficient protein, that there's hardly any meat in the product. Really concerned to find that it's mainly carbohydrate, very low on nutrients, can bring on diabetes and the lack of protein promotes muscle wastage. She's become much thinner and fragile in the last few months. The arguments against the high carb diet make a lot of sense now that I see the state my cat is in. Especially since this food is the only food she receives as I was directed not to feed anything else.

I'm concerned that she's literally going to starve herself and I'd be better off giving her a higher protein/fat diet and asking the vet for transdermal gel.

Does this seem like a sensible course of action? What sort of price would I be looking at per month for the gel and would I be able to buy it online with a vets prescription? She came to me at age 10 uninsured and i wasnt able to get insurance for her. I'm assuming the gel is available in the UK now.

What brands of food would you recommend I feed her, bearing in mind that she'll only eat dry food, we're based in the UK. She won't touch human food - I was given her when she was 10 and her previous owner had only ever given her biscuits and the odd bit of canned tuna (which she won't eat now) for her entire life, so I suspect it's too ingrained, she won't eat chicken either - i've tried.

Reading the posts I'm assuming that I should avoid food that contains fish and senior foods. Would some supplementing with kitten food be a good idea? I noted somewhere it's stated that elderly cats have the nutritional needs nearer that of kittens.

I'm really concerned and she's in a sorry state and seems to be rapidly deteriorating. Would greatly appreciate some advice.

I agree that you need to feed another food that your cat will eat. But this also sounds like something else -- potentially serious-- could be developing. You need to recheck with your vet and have the kidney and liver values checked as soon as possible.

I just found your site. Our almost 14 yr old tabby had the radio iodine treatment a month ago. She's gained some weight back and looks wonderful, however, she no longer plays. She's very picky about her food. We throw away more than she eats. She also has a cough. I don't know how to describe it.....I don't know if it's a cough or if she wheezing. Sometimes the episodes last as long as two minutes. She did this prior to the radioiodine treatment but now it's happening almost every day. One good thing is she is not vomiiting as often as she did before. She still drinks a lot of water. I miss our "playful" kitty. Thank you for any info you may offer.

At 1 month, you need to recheck kidney function as well as thyroid function. I would recommend a total and free T4, as well as a TSH level to make sure that hypothyroidism isn't developing. Talk to your vet.

My 4 years old cat was diagnosed with hyperthyroidism about 3 weeks ago, she didn´t have most of the symptoms, I just noticed there was something wrong because she was being a little agressive and verbal, the levels of T4 were at 4,1 . Two weeks ago we started the farmaceutical treatment with 2,5 mg of Thyrozol a day, but after 12 days on the pill, she started vomiting and getting facial rash. I´m looking for advice on what to do to keep her as healthy as we can while we wait for the radiotherapy treatment. I´m from Chile, and in our country there is only one veterinarian hospital that does this kind of treatment, so we have to wait for at least a month. I´m thinking on feeding her Hills Ideal Balance, that doesn´t have corn, soy, wheat or potatoes, only chicken, brown rice and veggies, with some raw meat for lunch. I´, willing to do everything I can to make her healthy again, she is so young and her doctor says her organs are in good shape and I don´t want her condition to get bad only because I have to wait to get her into treatment.

Honestly, I highly doubt that your cat is hyperthyroid. Less than 0.1% of cats are younger than 5 years of age, and your cat's T4 is borderline high. Remember that we all (both humans and cats) have our own normal range for all thyroid hormones, so it may be that your cat's thyroid values run higher than other cats.

Did your vet palpate a thyroid tumor? If not, I would stop the medication and retest in a month. If your cat was to see me, I'd measure a total T4, T3, free T4, and cTSH concentration to get an entire profile of the thyroid.

As far as diet for any cat (hyperthyroid or not), I believe that they should be fed primarily a canned food diet with low carbs and higher protein. Very few of the Hill's diets are adequate, in my opinion. That said, I also like to vary the brands fed (I never feed only 2 brand or flavor to cats but alter the brand and flavor every day).

Hi Dr. Mark, I'm the one from the last comment. I followed your advice to check for the diagnosis, and I took my cat to the doctor that brought the I-131 treatment to Chile. She said that my cats does have hyperthyroidism because of the palpable ( small) tumor. It seems that hyperthyroidism became very common in this country, as the matter of fact, there are one year old kitties with this disease.

Since my cat is allergic to thyrozol, the vet recommended the y/d for 3 months, until the radiotherapy ( we are on a waiting list until end of october). I'm really afraid because I know it is a defficient diet for cats, but it is my last chance of a treatment before the I-131, I've been feeding my cat mostly canned food and she seems healthy, but I know I cant control the disease by doing nothing.I want to hear your advice for this months of waiting.thanks dr, for the chance to ask a great doctor such as yourself about this.

Dr. Peterson,I am enjoying your blog. My 17-18 year old male cat had lost 2 pounds, dropping from 12 to 10 since last November and began showing signs and symptoms of hyperthyroidism. Our recent visit to the vet on 8/29 had indicated early onset of kidney disease and hyperthyroidism. Kidneys were palpated and one was smaller than the other. Thyroid was not able to be palpated as he is not a very patient patient, if you will. His urine was dilute and his specific gravity was 1.019, Amylase was 1308, ALT (SGPT) was 124, T4 was 4.6. He could not tolerate Methimizol and became very ill so we opted for i-131. The specialist had determined based on the blood-work and other tests that 2 mCi would be appropriate. Since Kidneys are the only organ that love the increased blood flow of a hyperactive thyroid, the goal was to decrease the hyperthyroidism without further compromising the kidney function. My question to you after reading this interesting article is what to feed him. Ive had him on senior Blue Buffalo dry (crude protein 28% min) with a tablespoon of wet food in the morning and evenings. Due to his kidney disease I was in the process of moving him over to hills K/D dry (22 % calories from protein) with a tablespoon of wet in the AM and PM until I read this article.

-Doesn't an older cat's kidneys benefit from a lower protein lower phosphorus diet?-I see per your blog an older cat can benefit from a diet more similar to that of a kitten, but what of one that is a geriatric, post i-131 and early onset of kidney disease? Taking what you have written in your blog, this puts me in the perplex situation I am in because I want him to regain his muscle and fat without taxing the kidneys further. What would you suggest?Thanks in advance!Kevin

I am not very familiar with phosphate binders. Would you recommend a calcium based or aluminum based?-could another solution be to add protein, such as cooked chicken to a low phosphorus diet such as k/d?Thanks for all your help

Wow alot of information. My cat 13 years old tabby, she was on meds 2x a day. Her behavior is quiet, not happy, hungry. Until retest and vet decide change to 1x a day. Her behavior is much better but still hungry. I am trying to find what food that make her full and not beg for eating every 30 min to 2 hours. I fed her with Beyond can food and dry food only chicken. Sometimes I fed her with Fancy Fest. So look like those both food have high iodine. I am little lost which brand that I should feed her to make her feel full. I see one comment that person use homemade lamb food. My heart hurt when she look at me "Please give me food". I gave her often few times a day average 5-6 times a day.

Hello, and thank you for this well-sourced and informative post. I like many others have a question related to my cat's hyperthyroidism. Blush (15/m) was diagnosed earlier this year with hyperthyroidism. While I believe it had been worsening over time (I never really noticed the symptoms which were in hindsight very obvious) health issues related to the toll it was taking on his heart came up very suddenly soon after his brother developed complications from diabetes and we put him on a strict wet food diet (just fancy feast pate, chicken or chicken and liver flavour). Because it was easier to feed the cats the same thing, Blush ate this too. I have no idea if it was just a coincidence but about a couple of weeks after switching to this diet is when Blush became very ill, and was diagnosed with hyperthyroidism and cardiomyopathy. I tried to give him methimazole as prescribed by the vet, but it had a very bad effect on his liver (his stool was noxious, loose, and more often than not either covered in or mostly composed of a yellowish slime). Tests indicated his liver function was extremely poor, and that he was one of the small percentage of cats who just cannot be treated in this way. He is now on a daily dose of atenelol and benazepril. He is also, as was recommended by the vet, on the Hills y/d diet. I'm well aware of the controversy surrounding Hills and I do not enjoy supporting what I see as corporate corruption, but I am also in a difficult position due to my cat's inability to take methimazole. I currently feed him the hills in small portions through the day (although the food is kept from his brother, as any dry food increases his blood sugar) and he gets a small portion of fancy feast day and night when his brother eats. I have noticed a recent return in certain behaviours that are associated with hyperthyroidism - Blush will howl at night. I have no idea if this is related to the FF or not. Howeveer, his muscles (especially in his hind legs) are becoming very weak. Further, during a time when he was ONLY getting the hills (wet and dry) he began to experience hair loss. This has led me to alternate between the two. I was wondering if you had any suggestions or recommendations as to what might be the best diet for him, considering the methimazole issue. As I understand it, diet is the only way to manage his HT. Thank you, and I apologize for the long-winded response... I really meant for it to be much shorter.

This entire post and conversation are a great resource! Thank you. I apologize in advance if this has been covered...I was reading Q & A up to a certain point and realized there were MANY more and I wanted to see if you had discussed herbal solutions with anyone yet. So, I will just ask. My calico is ~14-15 and newly diagnosed hyper. We started her on the methimazole at 2.5mg 2x/day. She seemed to tolerate it well at first. But we had to stop the medication after 2 weeks due to continued vomiting, of even just water, and loss of appetite. My intention is/was to do the 131-I, but my vet instructed me that Cornell will require ~3 weeks on meds to ensure stable renal function. She did see the vet at the 2 week mark, to give her some fluids and check her status, due to the circumstances. Her blood work at that time showed stable kidney function, but it was not enough time on the meds, and she was not yet euthyroid. They wanted me to try the Hills y/d--I said I preferred not...so we are using the transdermal. But while waiting for that script to come, I did some research and found info on bugleweed, alone and in combination with heart protective herbs, for use in hyperthyroid cats. I ordered a formula and began using it...I am using it at half dose along with the transdermal at half dose.

Do you have any insight on using such remedies, and/or with or without diet adjustment, and/or with the medication? My ultimate goal is still the 131-I treatment...but I have to maintain her on something/anything that will bring down her T4 levels and show stable renal function. She eats grain free--always has--and since being hyper (I didn't know it at the time) has been eating canned food (she wouldn't touch it before that). So currently, she is getting an assortment of what would be considered higher quality commercial foods. I am considering beginning to cook poultry for her, just as an adjunct to the other efforts. Your experienced opinion on this would be greatly appreciated. --Sorry this was long, I felt it best to give you the whole status. THANK YOU!

And, in follow up...is it fairly universal that a euthyroid state for ~2 weeks (by whatever means) or 3-4 weeks of methimazole without kidney function issues is a hard and fast requirement? I'm just thinking that if my cat ends up responding poorly again to the med (via transdermal), and if hypothetically she won't eat the food (that I don't want to give her anyway)--the radioiodine or surgery is the only option. I find it hard to believe that treatment would be refused just because renal function would be an unknown. Renal function problems occur in cats anyway...and it must be dealt with accordingly. The hyperthyroidism can't be left untreated, and I can't also believe any vet would rather a cat stay on a drug killing them over the chance for life with only 'possible' kidney problems. Just concerned that if we reach this point, I won't know what my options are. Thank you again. :)

Thank you. may I ask then, how do you choose to proceed? I see Dr. Lisa Pierson opts for I-131 regardless of possible kidney disease, as it will need to be taken into consideration anyway. And I see that a hyper state can exacerbate kidney disease. What do you suggest?

Find someone that you can work with, someone that can evaluate your cat's kidney status and give you an idea of what's going to happen once euthryoidism is restored. If your vet can't do this, then get a referral to someone else who may be able to help you.

My 13 y.o. cat was just diagnosed. Het T4 level is 12.2 (high), ALT (SGPT): 123 (high), Alk Phosphatase: 105 (high) - the last two, as I understand from online search, indicate some extent of liver damage. Platelet count: 83 (low), Differential: Absolute - I don't know at all what these mean but they are highlighted in bold typeface on lab report.

This is the first time I used this vet, and he doesn't want to explain anything. After I kept trying to get information out of him, he just said that my cat is aging and that he saw indication of this on the blood test. He did not comment on any other numbers on her lab report that were indicated as high or low, and was not going to mention the liver until I called the second time after doing online reading. He did not say anything about the kidneys and how they may actually be damaged too, even though it does not show on the blood report (if I'm reading it correctly)

He just said she is aging, liver is aging with her, put her on y/d (I won't), and if that doesn't work, try methimazole (just filled prescription). He wasn't even going to give me the T4 level until I requested to be given the lab report.

I just feel like this vet is on some strong tranquilizer with not a care in the world, while I'm thrown this bomb of learning that my beloved baby is very sick and declining.

--She also has arthritis, which I give her cosequin for. The vet had no other suggestions. Is it safe to use along with methimazole?

--Shouldn't she be checked for worms, parasites? What if they are contributing to her weight loss?

My nearly 16 yo cat was recently diagnosed with hyperthyroidism. She had been losing weight for some time, often throwing up early each morning before eating, wanting to eat frequently, yowling while she ate. The vet has started her on y/d dry food which she has accepted. She used to love fresh fish - will it be possible for her to ever eat it again? She looks so sorrowful whe we eat it and she can't have any - we always used to cook her a piece. It's too early to know if the diet is working, but she doesn't seem quite so starving as before. She sleeps most of the time.

Dr. Peterson- As I posted months ago, my 4 years old cat was diagnosed with hyperthyroidism, we tried thyrozol but she had a reaction, so we are feeding her with y/d for the past 7 months as we wait for the I-131 treatment. Her T4 levels have never been higher than 4.1, now at 2.4

In the last urine test, the vet found levels of borderline proteinuria (up/uc=0.4), protein in urine at 30 mg/dL . Specific density is >1,050 and BUN, creatinine and phosphorus levels in blood test have always come out normal and stable. No sympthoms, she drinks the right amount of water and urinates twice a day, about 70 ml, like a clock.

Less than 24 hrs after my cat got tested, I got an email from the vet prescribing enalapril (1.25gr a day) and basically telling my cat has CKD. Now she is drinking less water and urine volume is lower.I would appreciate your thoughts on the diagnosis. As a mom I feel the diagnosis was very fast and without further investigation. Borderline proteinuria can be cause by stress (we had a hard time at the clinic), it can be transitional, etc. Bacteria culture has not been sent to me yet...Can borderline proteinuria be the base of a CKD diagnosis itself?? without any sympthoms, levels of BUN, creatinine and phosphorus very stables, urine density higher than 1,050...

I have a 19 y.o. male tabby with athritis and diagnosed through bloodwork to have moderately advanced kidney disease and prescribed Hills KD and Royal Canin Renal. I knew about his kidney diminishment due to copious drinking despite eating primarily quality can food as well as the smell/quantity of urine in his box. He has never been overweight or skinny. I took him to the vet though to have his thyroid checked because he acted like he was starving all the time (feeding amount daily one 5.5 oz. can in two servings; he's a medium build cat about 9.5 lbs.) The bloodwork cleared him of HT. On the side of his neck for years I have felt a tiny bump. My guess was his chip had migrated. Unfortunately I couldn't have ther vet palpate it due to his high anxiety. This visit was a year ago. Since he went on the diet two things of note occurred: after reading this blog post I realized he was wasting away on a stupid LP diet, I put him on a high quality protein diet. And second: the lump has gotten noticeably bigger. I am convinced that he has a tumor on the left thyroid gland. The reason I am writing is I am wondering if a tumor could cause HT symptoms without showing in his bloodwork as HT? (I understand that HT can cause CKD symptoms but I believe the evidence is apparent he has this disease.) I am concerned about more vet trips and possible surgery because last vet visit he had to receive gas to get bloodwork due to his anxiety and it took him a long time to come out and be released to me (they were even surprised it took about twice as long). On the other hand I want him to be comfortable and have a quality life; I think it could better at this point in time.

So I'm feeling at my wits end here after reading all these posts. I have a 12 year old male with hyperthyroidism diagnosed 2 weeks ago and as of today had to stop the methimazole (repeated vomiting and tearing out tufts of hair, itching, refusal to eat). I was told to put him on y/d and I can't afford anything beyond y/d (and barely that as it is). Based on what I read here, the y/d lowers the thyroid stuff but he's going to slowly waste away because of the low protein? Are there any other resources or options you know of besides radiation or euthanasia?

My cat is only 7 years old and has been diagnosed with hyperthyroidism. I'm concerned bc she is still pretty young and I didn't expect her to have health problems yet. I put her on the medication but she developed facial scratching and anemia as a result according to the vet I saw. I put her on the y/d diet and so far she has been eating it. Is there anything else I should be doing for her? I want to make sure I am covering all my options.

FIrst of all, make certain that the diagnosis is correct (I"d do this with another vet(.

Second, a 7 year old cat should be treated with either surgery or radioiodine to remove or destroy the tumor. This is a progressive disease that will get worse with time and cannot be controlled long term in most cats with methimazole or y/d.

My 13yo cat was diagnosed with hyperthyroidism a few months ago (she had lost 3 pounds over a long period of time) and she had the I-131 treatment a month ago. Her T4 was 18.1 to start and the blood work shows it is now .8 which is on the low end, bordering on hypo, but we are hoping that over the next 2 months it will come up as the thyroid has time to grow back healthy. She has gained a pound since her treatment. Prior to the I-131 therapy the vet tested her kidney function with the SDMA test and her results were an 8. She felt comfortable at that number to proceed with the radioactive iodine injection. Following the treatment her results are now a 17 (which is slightly over high normal). I have been told that she is in early stages of kidney failure and the vet wants her to start on renal support prescription food. After reading your posts, I am concerned that putting her on a low protein diet is the wrong move since she has already lost so much muscle mass. Do you think in her case that phosphate binders is still the better choice?

Before you start to treat renal disease, they need to rule out hypothyroidism. Most cats that develop hypothyroidism after I-131 maintain a low-normal T4 (but less than 1.5 ug/dL). But these cats can be diagnosed by finding a high TSH level. Tell your vet to recheck again in a month and to redo a T4 and TSH. If you diagnose and treat hypothyroidism, the renal values will generally improve and dietary management of CKD is not needed.

If you have to manage renal disease, you could start with a phosphate binder added to the food, rather than switch to a low protein renal diet.

Thank you Dr, Peterson for what you do for us animal parents and our beloved animals. I did decide not to be paranoid about my personal experience with the atomic bomb and separating that with my cat getting 131. So I did the challenge with meds, but she began to puke and puke so horribly bad after four weeks, so I took her off but had the blood work done within one day. It said she had elevated kidney enzymes, well the vet was dumbfounded and said he would get back to me, that was five weeks ago, so I fired him, as he did not tell me to wear gloves when handling the meds, and he did not know why she was vomiting, like its fairly common for Hyper T and meds to cause vomiting and then he had nothing to say about her seizures, she has these horrible seizures and when I searched on the net I saw the same type and it was hyper T. So I fired him. She had to be rushed to the emergency last friday and put on a iv, and she is on seizure meds now, I want to do the 131, but now she has a heart murmur, I love her so much I slept in my car by the hospital in case she was going to die, I wanted to rush in and hold her and kiss her and whisper loving things in her ears as she died. Can I still do the 131 if she has elevated enzymes. I refuse to do hills diet. I am so grateful for what you do, answering these posts, I was a volunteer and worked for social change all my life, so I am deeply grateful for those who help others. I am going tomorrow to get the gel. Like I said in my first missive, I am bed ridden, and this cat is my sole/soul companion who keeps me company in my dark times. She is about 12, a rescue. Thanks doc.

About half of hyperthyroid cats have a heart murmur and about 50-60% have elevations of one or more liver enzymes. None of this means you can't treat with radioiodine if the murmur and liver elevations are due to hyperthyroidism and not due to another condition (which would be unlikely). Good luck!

Thank you doc, I am being cornered into doing 131, the gel at the lowest level on hour after application made her vomit violently, even after keeping food away for 12 hours, she vomited severely after a few teaspoons of food. Thank you, no need to respond. Will continue to read your whole site. Goddess bless you.

This has all been very informative. Link, my 8 year old cat, was diagnosed with hyperthyroidism a few months ago. We tried Felimazole but he reacted quite badly to this (skin sores and vomitting) so we 8 weeks ago he had radio-iodine therapy. Just got his latest blood work back and he is still hyperthyroid. We have been advised that it can take months to fully work but I'm plagued by thoughts it won't. I am not in a position to afford a 2nd round of treatment or even surgery. My vet mentioned the y/d food, which lead me here. Obviously now I am concerned about the potential weight loss should I need to use this. As the advice from Hill's says the diet works in 3 weeks, what would your opinion be of feeding y/d exclusively for 3-4 weeks then a high calorie diet for 1-2 weeks? I have been giving him Kattovit to try to get his weight back up post-treatment. I was suprised by his recent results as since treatment he has gained weight, his pulse is normal and he is more settled. Thanks for your time. Charlotte.

If you feed y/d to control hyperthyroidism, your cat cannot eat ANYTHING else. All of diets contain too much iodine. (Makes you wonder, doesn't that mean that iodine is important since it's in all foods?)

Talk to your vet. Most cats T4 values fall by at least half by 30 days and 75 percent by 2 months after I-131 treatment. If the T4 remains clearly well above the reference range at 3-4 months, then I would recommend re-treatment.

Thanks for the fast response. Before treatment his T4 was 197 and now it's 169. After reading all this info I'd like not to try the diet and if his T4 hasn't improved at 3 months post radiation, we're just going to have to find a way to afford another go.

My cat was diagnosed with hyperthyroidism about a year ago and refused to take the tablets, he was then put on yd, wet and dry , but now will only eat the dry and even refuses this most of the time. I see hinm losing weight but our vet says if he is hungry enough he will eat it. He doesnt like it and is very subborn to the point that he will starve rather than eat this food.

Can i feed him a home diet like chicken, fish, tuna etc and give him a suppliment which i can break up over his food to help. I feel he is fading away and our vet is not helping at all.

Of course, I would feed your cat something that he will eat. The y/d is not going to work if he will not eat it. I'd recommend that you rule out other problems that cause a poor appetite. Talk to your vet or get another opinion.

My 13 year old diabetic cat was diagnosed with hyperthyroidism a little over a month ago. He had none of the classic symptoms and the condition was detected by a routine wellness panel that tested for t4. He is slightly overweight and has a beautiful coat with no hair loss. The only symptoms he had developed was a new intolerance to heat (he is strictly indoors) - any rise in room temperature or him lying in the sun from the open curtains would cause him to pant. This was new. He would also begin to pant with any stressful situations (vet visits, etc.) which was new for him as he had always been very friendly and tolerate visits to the vet with no problem. On his last visit to the vet he became so distressed the vet was concerned of respiratory collapse. His vet has since been making visits to our home which has greatly reduced his stress. His only other symptom was some diarrhea which now seems to have been resolved - he is on a daily dose of fortiflora. His initial t4 was 10. He was started on methimazole transdermal gel 2.5 mg twice a day. follow up t4 2 weeks later was 11.3. Dose was increased to 5 mg twice a day. He had his two week t4 drawn yesterday which was 11.8. I am wondering if his diet has something to do with it. I have been trying to follow the high protein low carb recommendation which he was basically already on secondary to his diabetes. He had been eating a lot of canned food that contained fish. I did begin reading labels after diagnosis and avoid any foods that contain fish. One thing I did notice is that all canned foods seem to contain salt and potassium iodide as additives. Could this have something to do with it? Is there a specific brand or type commercial food that may be beneficial for him? I don't think that he will tolerate the y/d food as he is quite finicky. I did notice yesterday that one of the beef foods that he was eating contained fish so I cut that food out. Also, some of the food I was feeding contained soy and I cut that out as well. What are your thoughts on his t4 rising after 4 weeks on the methimazole gel? Any help would be greatly appreciated. Thank you.

Thanks so much for your reply! I forgot to mention that the reason Rico was started on the transdermal form of the medication is that he is a little difficult to pill. He is completely intolerant to any compounded liquid forms of medication - he throws up almost instantly due to the taste. He also has a history of tongue ulcers to to a past history of a compromised immune system and the Feline Calici Virus. He is currently on 250 mg L lysine twice a day to help keep the virus in check. He is also on a very low dose of prednisolone (.06 mL) daily to help with the inflammation. He does have a bit of fur inside his ears and my vet was questioning if the medication was absorbing properly. She suggested we shave the insde of his ears to see if that helps with the absorption. She said she will recheck his T4 levels in one week and if they haven't improved then he needs to be transitioned to methimazole pills. Do you think this is reasonable or do you think I should have him switched to the pill form now. I am quite concerned with his high T4 levels and this all is making me very nervous. Thank you so much!

Hi Dr. Peterson. Rico was switched to methimazole tablets 2.5 mg twice a day to start. She started him back on the lowest dose when he waa switched from the transdermal with a t4 due in two weeks which is due Monday. He seemed to be doing ok but last night he was lying in my home office (which is a little warmer than the rest of the house but wasn't overly warm) & he started panting. I took him to a cooler room & his breathing improved after awhile. He has also been having episodes of diarrhea. He was given a sub q injection of Buprenex yesterday for his mouth pain. In researching the drug I read that it is contraindicated in cats that have thyroid problems but another site said contraindicated in cats with an underactive thyroid. My vet assured me it is safe to give. Of course I trust her but was just wondering what you thought about all of this?

Oh wow! This was so awesome to read! I have a question! My cat (8 years old) is currently on the y/d Hills pellets and soft food cans. She is super overweight though (which is odd to me because most people complain of cats being too skinny with hyperthyroidism) but the vet said it is because we were able to catch this relatively early on before it got to the point of her losing weight. Her initial T4 level was 93 and it went down to 23 in about a month and a half, so we are so happy about that. However, with her hyperthyroidism came some behavioral issues that have not cleared up as the T4 levels went down so now we aren't sure if they're behavioral or her trying to tell us something. She constantly cleans stuff, herself, our poor other cat who is super stressed from constantly being groomed (and has lost 1,5kg's in two months cause of this), and our hands too. We are a very clean family, haha, but I am worried about our other cat who is stressed by the cleaning. Another behavioral thing we noticed is she became very vocal and still does a trilling cat sound pretty m constantly and meows often sounding very distressed. We don't know what to do! If you have any advice please let us know.

Most cats on y/d are not completely controlled so your vet might want to measure a free T4 (together with the total T4) on your next recheck. Do you really want to feed this diet for the rest of your cat's life? That could be many years at only 8 years of age...

Hello,My 13 year old cat has this year been diagnosed with the thyroid disorder and it was recommended to feed the Hill's diet to him. A few months later on this diet, while his thyroid is maintained, he is not himself at all, and recently lost weight, is lethargic and zombie like. His pupils are dilated constantly. I just had him at the emerg today and everything was pretty normal and thus points to neurological issues, as his pupils are not responsive and he is sensitive to touch on certain areas of his body. I worry that the low protein diet has contributed to this. He has always been a robust eater and a large cat - muscular and 30lbs in his prime. I wondered if you had heard of nerve problems related to protein deficiency. I didn't feel 100% about using the YD exclusive diet but obviously for financial reasons it was the choice we went with. I am still considering the radiation but now we have to deal with this neurological issue first. Any insights would be helpful as I believe he still has a lot of years left in him. :)

If you haven't already done so, I'd measure blood pressure and do a good eye exam to make sure that his eyes are ok. A referral to an neurologist would be the best plan. This isn't likely related to the y/d or directly to the hyperthyroidism (other than possible secondary hypertension). In any case, this is serious and you cat needs a workup.

I followed your earlier advice and had my vet switch my cat to methimazole pills instead of the transdermal gel which was not working at all. At diagnosis his T4 was 11.8. It went down to 5.2 on 5 mg twice a day. His dose was increased to 7.5 mg twice a day and his T4 went down to 4.7. Dose was increased to 8.75 mg twice a day and his level went down to 4.2. My vet said she was comfortable with this level and wants to keep him on this dose for now because he is close to the maximum dose of methimazole - she said the maximum is 20 mg per day. I am just curious if you agree with this dosage? Also, do you ever recommend putting any of your cat clients on milk thistle as a precaution due to the potential harmful effects of methimazole on the liver? Thank you for your most informative site!

There is no upper dose, but I've never gone higher than 30 mg. This high dose means that the tumor volume is large and likely continuing to grow. I agree that the 4.2 isn't too bad but I'd recheck again in a month and then increase the dose if higher.

Thank you for your response! Last night I made a disheartening discovery - I found what looked to be some pill remnants on and near his bed. I thought I was being diligent in getting the pills down but somehow he outsmarted me and apparently was able to spit some of the pills out. I think this happened in the last few days but of course I can't be sure. My vet wants me to continue the dose and have his T4 checked next week. I bought the pill pockets and that seemed to work better. I am considering the I-131 treatment. My vet thinks I should wait a little before having that done as he is diabetic and has a few other issues we are trying to work out.

Dr.Mark,Unfortunately I must feed my cat yd. Hyperthyroidism was causing seizures. My cat was allergic to th thyroid medication. The yd is helping the seizures but my old cat has the muscle and protein deficiency you wrote about. Is there any iodine free protein source? Recently his appetite went down and he vomits anything he does eat. I'm worried.

I have been battling w/HT for 4 yrs now but didn't know that was the problem. I thought it was IBS. She is a shelter kitty so not positive on her age but per shelter she is 14 but the vet thinks she's around 10. In April she was diagnosed w/HT. Dr started her on meds 2x's daily. She responded well. We were on track, she was gaining weight, acting like a normal cat. I'd put the pill in a pill pocket & she'd gobble it up. 2 weeks ago she started rejecting her meds and food. She's always gotten bored & I'd rotate her food & she'd start eating again. Not this time. For a cat that is literally back down to skin & bones in just 2 weeks, she is like wrestling a rhino to get that pill down her. There are very few foods on the shelves that I have not tried at least once. The last 3 days have become critical as she is starting to wobble when she walks & her eyes have sunk back. To complicate this my area was just hit by Hurricane Matthew so everything has been shut down since Wednesday. I don't know if she will make it to Monday. Any guidance that may help me help her hold on until I can get her to the vet on Monday would be extremely appreciated

My 9 year old cat was just diagnosed with hyperthyroidism in our last regular check-up with the vet on 9/30/16. I have been endlessly researching hyperT in cat, reading your blogs and articles finding out amazing information so thank you. But I do have a few more specific questions specifically regarding his case and would love your input if able.

Since Gregory is now a "senior" we completed the senior blood work-up at our last vet visit on 9/30. She added on the Cardiopet pro-BNP due to an audible arrhythmia noted on his last 2 evaluations.

The values of concern are: Total T4 is 4.5 (0.8-4.7)Free T4 (ng/dl) which is 3.4 (0.7-2.6 range)Free T4 (pmol/L) which is 43.8 (9-33.5 range)

Clinically he is showing few if any of the regular signs of hyperthyroidism - coat is perfect, no weight loss, no vomiting or diarrhea. He sleeps all day and still snuggles as per usual. He has become a bit more active overnight between 1-6am and has always been very very excited and noisy about his food. But that does vary based on my schedule and his.

We had a cardic work-up done to determine why Cardiopet pro-BNP was elevated but ECHO revealed 5mm thickness in heart wall which vet said was normal, normal EKG, HR 190-200bpm, Bloodpressure 180mmHg. There was a notable E:A wave inversion on the ECHO, but did not require any treatment at this time. She also felt some of these values could be elevated due to stress. The cardiologist also noted a thyroid slip on palpation but was unsure if this was a tumor or possible normal enlargement.

I have been looking into I-131 treatment and would be willing to do it when he is ready. However, I am concerned that since his numbers are fairly low or borderline and very few if any clinical signs are present, should I be treating now? or wait and monitor T4 levels until they rise? I do not want to begin treating him too soon, but also do not want further heart or kidney damage to occur while I am waiting for symptoms to come on.

We have only had 1 round of bloodwork showing elevated levels at this time and that was 1 month ago. Weight and clinical signs have remained unchanged this month. I am worried to treat too soon for fear of the tumor returning or potentially putting him into a permanent hypothyroid state.

Dr. Peterson,My now 16 yr. old cat was diagnosed with hyperthryoidism about 1.5 years ago, at age 15. The vet started her on oral methimazole and she went into a severe decline. Her white blood cell count was as low as someone on chemotherapy (per the vet). He said he has never seen such a reaction and it is very rare. I put her back on regular food (whatever she would eat) and she gained some weight and improved, then she had to be on the Y/D Science diet exclusively. At the time we felt that the radioactive and surgery were cost prohibitive given her age. Now at age 16.5 her latest blood work shows the hyperthryoidism not very well controlled and she is at a very low weight, 6 lbs. down from 7 one year ago, down half a pound from 6 months ago. She does eat the Y/D dry. No muscle mass although still able to walk and jump on lower furniture. The vet thought that perhaps she would tolerate the transdermal methimazole and we could try that; he is going to contact some universities to see if that might work in a cat with such an unusual reaction to the pills. Have you ever seen that kind of reaction to methimazole and would the transdermal be any different? The only other option I can see from reading extensively and talking to my vet would be the expensive interventions.

My vet had me put my cat on y/d due to bad reaction to methamzole. I was told my cat needs to be on y/d for two months to normalize the thyroid levels and then blood test to confirm kidneys are OK to do the i131. I was never told the y/d needed to be discontinued before the radio iodine TX. I'm wondering if I should bypass these two months of y/d and go straight for the radiation without waiting for kidney levels on normal thyroid levels.

Thank you for helping us kitty moms, Dr. Peterson! I've read thru everything but I still need to clarify that I'm Understanding it right. Big Kitty (not big anymore) is 15 & she was diagnosed with HyperT. the vet said we caught it at the right time because her kidney levels were only 2 over normal range.. she was prescribed Methimazole twice a day & the vet gave us Hills K/D wet food. Well Big Kitty will not touch the hills K/D food.. she much prefers her fancy feast I guess. So if she won't eat the K/D do I need to find something she will eat that's high in protein to help her gain weight back? Thanks!

Your cat will gain weight and body fat after controlling the hyperthyroidism. A higher protein diet (FF classic flavors are high in protein). You may need to add in a phosphate binder to control high serum phosphate levels to slow progression of kidney disease. Talk to your vet.

Hello Dr. Peterson, thank you for this page! My 15 year-old female cat has been healthy til a few months ago, but always threw up her food at least 2-3 times a week (from eating too fast I presumed). The rest of her was looking great, with plenty of energy and shiny coat so we didn't worry. She was on a high-protein dry cat food (45%). Recently she started throwing up daily, her pupils won't retract anymore, and now she's loosing her balance. At the recommendation of the pet store, we switched her to a new food with less protein (35%), and she's been getting worse MUCH faster: now she's very wobbly too. And owing to your article, I can see why: she is loosing her muscles and getting weaker by the day! :(Yesterday our vet diagnosed hyperthyroid with a number of 8.2... Very high. The choice given was y/d or the meds, so we picked the meds (syringe 2x/day), but I also need a great new food for her. Do you think wet food is easier to digest, for her sensitive stomach (she has been throwing up occasionally for years)? Or is dry food more nutrient-dense, so she can get enough nutrition? Or can I combine both: wet food for meals and dry food for snacks in-between, for example? Thank you!

On catinfo.org, they make it very clear that wet food is the only respectable option for conscientious cat owners because of how it meets the requirements of the obligate carnivore. We were feeding Punkin and Peanut (now 13 years old) Fancy Feast for about eight years until Peanut started to show signs of hyperthyroidism which was confirmed by our vet. Then I learned about the dangers of soy in the diet of a cat and we immediately quit feeding them Fancy Feast and went to the Solstice products. More expensive yes, but you can pay now or you can pay later with a sick animal on your hands as well as high vet bills. We then learned about how pull-top cans have been linked to hyperthyroidism in cats. However true or not, we decided it was best to avoid the canned food whenever possible. We started feeding them Rad Cat raw poultry and they really liked it for about two months, then began demanding other things (you can tell because they'll just stop eating something and you wonder why). Then about two weeks ago we learned about the benefits of bone broth, so we cooked down a whole chicken, following the instructions found online. Combined with the meat from the carcass and the broth, the cats are really enjoying it and there seem to be fewer health issues, such as vomiting, diarrhea, etc., with Peanut, the HT cat. Ultimately we're learning variety is the key, but to avoid anything that stresses the thyroid, such as tuna because of the amount of iodine. And remember, the kind of soy used in cat food is also found in human food and it's no good for either of us.

Our 14 year old male cat has hyperthyroidism reading of 132 [normal 0-60] and the radioactive treatment, surgery and pill taking is not an option for this always indoor cat - or for us and our budget too I selfishly admit.

We have fed our 2 cats of same age 'higher quality?' - or higher priced it seems dry food and more recently Royal Canin Indoor seniors dry food thinking it was good for them - I should have read more a long time ago. His life partner of similar age died while we were away in mid 2017 and I now suspect she had same problem as he is showing.

After reading tons of info and trying the Hills YD diet which he hated and so do I.

I am now giving him Ziwi Peak rabbit and lamb canned food which has high animal protein and lower than normal iodine 0.82mg per 100g and I finally having him eating well and looking happy.

His kidney reading was on the high side of normal so I suspect he has problems there too.

My intention is to give him a happy well fed home life - without the stress to him of the other treatments. My main concern for him is minimising/eliminating PAIN.

Dr. Mark E. Peterson

About Insights into Veterinary Endocrinology

This blog is written specifically to serve veterinarians and veterinary technicians. I've divided the posts into 3 types: (1) my insights into specific endocrine issues, (2) Q & A posts that deal with questions I've gotten from veterinarians, and (3) reviews of current endocrine publications (with my comments and "insights").